Yes I see on its flight history SP-RKD has one flight, RYR753 showing as 48C131 all the other flights for it are showing as the correct 48C123

I can only assume there was a glitch on the RB24 system which showed the incorrect hex code

The aircraft was an unknown when it took off from Stansted so should have had no aircraft details then. I noted it taking off and raised a query on the mode-s forum at 1503 and received a reply at 1510 advising it was SP-RKS and the c/n was unknown at the time subsequently advised at 1604 that it was 44704 ex EI-FIS and the details were entered into the database

As stated SP-RKD was added to the database 22/11/19 so can only concluded that the RB24 server got itself confused somehow

I cannot see that SP-RKS has made any further flights since

Database entries for both aircraft showing the date and time of last change attached for reference.